For which of the following colours will the magnifying power of a microscope be maximum?

$A$ thin convex lens of focal length $5 \, cm$ is used as a simple microscope by a person with a normal near point located $25 \, cm$ away. What is the magnifying power of the microscope?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: For a simple microscope,the angular size of the object equals the angular size of the image.
Reason $R$: Magnification is achieved as the small object can be kept much closer to the eye than $25\, cm$ and hence it subtends a large angle.
In the light of the above statements,choose the most appropriate answer from the options given below:

For a compound microscope,the focal lengths of the objective lens and the eye lens are ${f_o}$ and ${f_e}$ respectively. The microscope provides magnification when:

In a Ramsden eyepiece,two planoconvex lenses,each of focal length $f$,are separated by a distance of $12 \ cm$. The equivalent focal length (in $cm$) of the eyepiece is:

Magnifying power of a simple microscope is (when final image is formed at $D = 25 \ cm$ from eye)